It is known to provide closed loop pressure control in a hydraulic system by monitoring the hydraulic pressure at a point in a hydraulic circuit, comparing the measured pressure with a desired pressure, and controlling the electrical current to an electrically operated valve, such as a solenoid valve, to open or close the valve to adjust the pressure in the system towards the desired pressure.
It can be a problem with such systems that known pressure transducers have a temperature dependent characteristic, so the exact hydraulic pressure cannot be accurately measured.